code: def __init__(self):
      self._string = io.StringIO()
      self._string.write("[")
  
file_path: FATE/python/fate/arch/federation/message_queue/_datastream.py
imports: import io
  import json
  import sys
label_desc: Use image node_id 1 to create a new Datastream object from inherited base classes: object with example: obj = Datastream()